Unbreakable
by Kariah Bengalii
Summary: Sirius and Narcissa make an Unbreakable Vow that they get married when they're thirty if neither of them is married before then.
1. The Vow

**Summary: Narcissa and Sirius make an Unbreakable Vow when they're about to go to Hogwarts that if they're not married by the time they're twenty five, they'll marry each other.**

**Author's Note: Yup, it's a Sirius Black/Narcissa Black fic. If you don't like it, don't read it, and if it inspires you, please let me know the name of the fic, because I love me some Narcissa Sirius Blackcest! **

**Another Author's Note: I'm using artistic license to get Narcissa and Sirius to be the same age.**

**Yet Another Author's Note: By the way, some of the chapters in this fic are ridiculously short—like the next one. I really don't particularly care if you don't like them that short, because this fic is more like a stream of memories than an actual story. There are just five moments in time that make up this story, so if you don't like the length of the next chapter, tough, I'm the author, not you, and if you want to do better, be my guest!**

**Disclaimer: I am not J.K. Rowling and do not own anything that belongs to her, nor do I claim to. I do own the plot, though. The idea is mine, all mine. *Hugs idea and cackles evilly* **

CHAPTER 1—The Vow

"Siri," Narcissa Black called to her cousin, who had just arrived with his younger brother, Regulus.

Sirius Black hurried over to her. "Hi, Cissa," he said, and then playfully ducked under his mother's arm to disappear into the living room.

"Siri!" Narcissa ran after her cousin, ducking under her aunt's arm around the other side, leaving Walburga Black to blink at her sister in astonishment at their twin bad parenting skills.

Narcissa caught up to her cousin and tackled him, slamming him into the couch. "Oof! Cissa…" he complained.

Narcissa eased up slightly and Sirius twisted around, pinning her into the same position she had just held him in.

Bellatrix walked in just then, and grumbled something about her 'immature sister and cousin'.

"What's that, Bella?" Sirius asked.

"I said, you little idiot, that you and Narcissa are going to be good for each other. You know, when you can't find anyone else…" she added sarcastically.

"Trix, I'm not going to be with _him_," Narcissa said.

"Yeah, I'd never—" Sirius began, but Narcissa slapped him. "Hey—" he started again.

"Whatever. No one would marry either one of you, anyway," Bellatrix said evilly as she started towards the door.

"Of course someone would marry me!" Narcissa complained at her sister's back.

"Suuuure, you can think that, honey," Bellatrix cooed.

"Here, Narcissa," Sirius said after a brief pause. "How about this? When we turn twenty-five, if we're not married, we have to marry each other, as long as the other is not married either, within…a year?"

Narcissa blinked at her cousin. "Okay," she said, "but we have to do this thing called an Unbreakable Vow. I heard Bella talking about them."

"Okay," Sirius said.

"Do you, Sirius Black, promise to marry Narcissa Black when you turn twenty-five, if you're not married, as long as she is not married either, within a year?"

"I do," Sirius said with great solemnity. "And do you, Narcissa Black, promise to marry Sirius Black when you turn twenty-five, if you're not married, as long as she is not married either, within a year?"

"I do," Narcissa grinned.

"What did you _do?_" Bellatrix gasped, having heard the exchange.

"We said we'd get married if we weren't married by the time we were twenty-five," Sirius said.

"I know that, you idiot!" Bellatrix hissed. "That is an Unbreakable Vow! Don't you get it? It's _unbreakable_! You'll die if for some reason you don't get married! What if you're betrothed, Narcissa? What if you are in some legal matter or another and you are in no circumstance to marry my sister, Sirius? Oh, good god! You two are such idiots!"

Sirius and Narcissa both looked at their feet, disliking Bellatrix's reprimanding tone.

"If we're lucky—and god knows I hope we are—then you two managed to do it wrong. If not, then we'll just have to plan for this circumstance and make sure Narcissa gets married before this even turns into an issue. Sirius, your birthday is later, and your wording should have made it not an issue if Narcissa is married, but we'll need to make sure you get married right away as well. I won't tell Mother and Aunt, because I know that they both feel horrible having managed to raise you like they did, and I don't even want to think how they'd feel if they learned you two managed to get yourselves into the problem that you did."

"Cissy, Trixie, Sirius," Andromeda called from the next room. "You have to come eat now."

"Coming, 'Dromeda," Sirius called.

"Yeah, Andi," Narcissa said, "we're coming!"

And they all went to sit down and eat, with three of them hiding a secret that would determine the direction of their lives.


	2. Sirius's Fate

CHAPTER 2—Sirius's Fate

"GRYFFINDOR!" the Sorting Hat yelled, and the entire school seemed to gasp in disbelief. Then, Gryffindor house clapped and cheered for their new house member—a Black. Sirius Black.

* * *

><p>"SIRIUS BLACK!"<p>

Sirius cringed and almost ran back out the door, but instead decided to face his fate and walked towards the voices. The very, very, unhappy voices.

He couldn't sit down for a week.

* * *

><p>Finally, Sirius was through. He packed up and went to James Potter's house, where he stayed until he became of age. He was disowned, but that didn't matter. He couldn't live with those abominations of people that called themselves his parents. Or, rather, they <em>had<em> called themselves his parents. Now, they had only one son, and his name was Regulus Black.


	3. Bride's Feelings

CHAPTER 3—Bride's Feelings

Narcissa looked in the mirror in her room. She looked beautiful, she supposed, but all she knew was that she was alone. Andromeda had been her closest sister, but she went off and married a muggleborn and got herself scorched off the family tree. And Sirius, her closest confidant and ally, ran away and got himself disowned. So no one cared anymore. No one cared about her.

No one cared that she was now betrothed, and she hated her husband. Most people didn't know. After all, who would bother to ask? She looked happy. Little did they know she knew she had to act that way. Appearances, after all.

Bella went and got married to Rodolphus Lestrange, and kept going about some 'Dark Lord' and how she had to get Narcissa to meet him after she got married. Narcissa was worried, to say the least. The prefix 'Dark' to Lord was rather disturbing, to say the least.

Anyway, Narcissa was sad. Today was her wedding day, as well as Sirius's birthday. She didn't keep track of the years anymore. She simply kept track of the months that flew past her and crawled by at the same time. She wouldn't be able to tell anyone how old she was if they asked.

Today was her wedding. It wasn't supposed to be like this. She was supposed to have Andromeda and Sirius here with her. Her family, her real family. To everyone but them, she was simply something to be owned, possessed, told what to do. She didn't have the backbone that they possessed. She simply didn't. She wanted someone who would tell her what to do so that she knew. She didn't like not knowing what to do. She just wished that that person would have her best interests at heart. Her mother didn't, and her father was long dead. Her soon-to-be husband wouldn't, and she knew her sister, Bella, didn't.

It was her wedding day, and, oh, how she longed for Andromeda to be her Maid of Honor, and for Sirius to simply be here. She missed them both so much.

Her wedding. They were probably off someplace together right now, talking about it. With Andromeda's husband and their child. They were probably talking about how happy she was, and how glad they were that they'd gotten out. They probably didn't like her anymore. She hadn't had the guts to run with them and leave Regulus and Bellatrix the heirs of the family, to try and make something of herself on her own, without her family's help.

But today was her wedding, and she hadn't spoken to either one of them for forever. Did they even remember her? God, she wished she could talk to them before she got married. Her last ties to them were her name and her blood, and she knew she would lose one today. Today, also, she realized, that she would, eventually, lose her blood. She would die somehow, and Andromeda and Sirius would have no more ties to their weak sister and cousin, respectively. It was better this way. Really.

Today was her wedding. She had to marry that awful man, that horrid man, the man who'd pursued her sister, Bella, and then when Bella had wed Rodolphus, promptly turned his attentions to her. She was sickened. He thought of her as some trophy, some possession, some tie to the 'Most Noble and Ancient House of Black', nothing more. He didn't want her. She could be ugly and emancipated with some horrible disease and he wouldn't care. She would tie him to the Blacks. As long as she could give him and heir and a tie, he would be happy. But, oh, how she wished today was not her wedding day.


	4. Wedding Interrupted

CHAPTER 4—Wedding Interrupted

"…speak now or forever hold their peace."

"Oi!" Sirius said, stepping from the shadows. Her family looked outraged to see him there. She saw his lips move as he mumbled a shield spell, not a second too soon as Bella's spell hit it and dissolved into it, the magic cast at it going back into the shield to power it. It was a very advanced spell.

"He has a right to speak his piece," the priest said.

"Narcissa," Sirius said, ignoring the bristling of both Narcissa's mother and sister at his impudence, "you can't marry him."

"Why can't she?" Bellatrix demanded.

"You see, Narcissa, it's my birthday today, and I was born just a few minutes ago."

"So what?" Narcissa's mom yelled at her ex-nephew. "You're not related to us anymore!"

Bellatrix looked between Sirius and Narcissa, a look of horror in her eyes. Narcissa simply looked at Sirius, an almost-daring-to-be-hopeful expression on her face.

"You're older than me, Narcissa, and neither of us is married," Sirius pointed out.

Narcissa simply looked at him while her mother shouted, "She's in the process, you moron! She's getting married this instant!" Turning back to priest, she said, "Continue."

The priest knew that the matter was not resolved and he should not continue, but she was rather scary, and, screw the common practice, these two were getting married to save his hide. "Do you, Lucius Malfoy, take Narcissa Black to be your wife?"

Lucius looked at Narcissa's irate mother and answered, "I do."

"Do you, Narcissa Black, take Lucius Malfoy to be your husband?"

"I do not," Narcissa answered.

"You _**WHAT?**_" Her mother shrieked at her, glaring at her.

Narcissa just had time to stare at Sirius pleadingly before her mother pulled out her wand.

"_Adhibenda alica clipeo protegere!_" Sirius shouted, pointing his wand at Narcissa. Her mother's loud curse absorbed into the shield so strongly that the shield, unable to take that kind of energy, bent out and exploded, and sent the majority of it back towards her.

Sirius yelled, "Narcissa!"

Narcissa ran to her cousin's side, ignoring everyone that lunged after her, knowing that Sirius would take care of them. Reaching his side, she saw that, indeed, there were quite a few bodies lying motionless on the ground with ropes around them or deformed legs or covered in something or another or people that were simply stupefied.

"Sirius! I thought you and Andy had forgotten about me!" Narcissa cried, sobbing into her cousin's chest.

"We didn't, Cissa, but if you wouldn't mind, I'd prefer to have this conversation where we aren't likely to be killed."

With that, he cast another strong shield spell and hurried Narcissa out of the building, from whence he side-along Apparated her to Andromeda's house.

**Author's Note: 'adhibenda alica clipeo protegere' translates literally from Latin to ****'****shield ****spell ****to be used ****to protect'. At least, according to google translate.**


	5. Wedding Uninterrupted

Chapter 5—Wedding Uninterrupted

Two months later, with Andromeda and her husband's blessing, Narcissa was wearing another gorgeous white dress and a veil, ready to marry her cousin. She loved Sirius. They were perfect together. Amazingly, she even got to keep her last name. She'd received quite a bit of help from Andromeda and Sirius in securing a good part of what should rightfully be her part of the Black family fortune.

In fact, she and Sirius were set for life, although he insisted on working because he wanted their great-great-great-great-grandchildren still set for life. His insistence really was quite adorable.

This time, when she was asked if she would take Sirius as her husband, Narcissa smiled and readily answered, "I do."

With the fateful "You may kiss the bride," Sirius swept her into his arms and kissed her passionately. Andromeda and Ted Tonks and their baby daughter Nymphadora, and James and Lily Potter and his parents, Remus Lupin, Peter Pettigrew were the only ones in attendance, so it wasn't frowned at.

When they walked out of the church, Narcissa was happy. She knew her cousin was protect her—he always had, after all, and they had money to make it, even with her spending habits. She had family that cared about her and not appearances surrounding her, and real friends. What more could she want?

**A/N: If you've made it this far, you've evidently finished reading my story. Thank you for taking the time to do so, and if you've got the time, please review!**


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